1. Field of the Invention
This invention relates to a silver-oxide material for electric contacts for use in switches applied to various types of electrical and electronic apparatus, and more particularly to a silver-oxide electric contact material for use in switches for high current of 5 A or more.
2. Prior Art
Conventionally, a great many electrical contact materials for use in switches for high current have been proposed and used in various electrical and electronic apparatus. Among widely used electric contact materials for switches for high current, there is known, for example, by Japanese Patent Publication (Kokoku) No. 55-4825, a silver-oxide electric contact material which is formed by subjecting an Ag alloy consisting essentially of, by weight % (hereinafter the percentage is represented by weight %), 5 to 10% Sn, and 1 to 6% In, and, if required, 0.01 to 0.5% Ni, and the balance of Ag and inevitable impurities, to an internal oxidation treatment in which the Ag alloy is -0.5% Ni, and the balance of Ag and inevitable impurities, to an internal oxidation treatment in which the Ag alloy is soaked in an oxidizing atmosphere at a temperature of 650.degree. to 750.degree. C. for a predetermined time period.
Further, there is also known from Japanese Provisional Patent Publication (Kokai) No. 58-110639, a silver-oxide sliding contact material (sliding current-carrying material) which is formed by subjecting an Ag alloy consisting essentially of 0.5-15% at least one element selected from the group consisting of Cd, Cu, In, Mn, Sb, Sn and Zn, and, if required, 0.1-3% at least one element selected from the group consisting of As, Ba, Mo, Pb, Se and Te, and/or 0.01-0.5% at least one element selected from the group consisting of Fe, Ni and Co, and the balance of Ag and inevitable impurities, to an internal oxidation treatment under the same conditions as mentioned above.
In recent years, there has been made a remarkable progress in the development of electrical and electronic apparatus having improved performance and prolonged service lives. Accordingly, there is an increasing demand for electric contact materials for high-current switches use in these electrical and electronic apparatus, which have improved deposition resistance and consumption resistance.
In actuality, however, most of the conventional electric contact materials for high-current switches inclusive of the former known electric contact material mentioned above do not have sufficient deposition resistance and consumption resistance to satisfy requirements imposed by recently developed electrical and electronic apparatus.
Further, the latter known sliding contact material mentioned above is used for contact chips of a commutator of a small-sized electric motor, i.e. as current-carrying chips for carrying a current as small as 100 mA or less. As a result, if the latter known sliding contact material is used as contacts of a high current switch which switches a high current of 5 A or more, it will result in a significant amount of deposition such that the contacts cannot be practically used.